You should use recorded delivery service or registered post only where

the document in question is of such a special nature as to warrant the use of registered post, or

the member of the public forwarding the original deeds and documents requests its return by recorded delivery service or registered post.

If you need to use the recorded delivery/registered post service please take the letter to the post room by hand for them to send the letter by recorded delivery/registered post.

The post room keep a log which shows all the consignment numbers of post we
have sent by recorded delivery. You may find it useful to check this if a
customer says they have not received something that was sent to them recorded
delivery.